In late 2370, the Cardassians deployed one of these missiles to destroy a Maquis munitions base on the PlanetoidAlpha 441 in the Demilitarized Zone. Although the Maquis threw every weapon available at the missile, it proved unstoppable due to the combined benefits of its strong defenses and its advanced computer. The missile failed to detonate upon reaching its target – the Cardassians had used an old-fashioned kinetic detonator in the design, which malfunctioned, and the missile simply drifted into orbit around the planetoid instead of destroying it.

There, Maquis member B'Elanna Torres managed to board the weapon, and spent nearly a month reprogramming its computer and upgrading its systems, and eventually nicknamed it Dreadnought. She completely reprogrammed the computer to work for the Maquis, and changed its vocal subroutines so that the computer sounded like her, as she claimed that she had gotten sick of listening to the "ugly" male Cardassian computer voice.

Once she was completed with refitting and upgrading Dreadnought, she sent it, without authorization from Chakotay, her commander, to attack the Cardassian fuel station on Aschelan V. The missile's evasive attack route took it through the Badlands, and it inexplicably disappeared.

It was not realized until nearly two years later that Dreadnought had been abducted by the Caretaker and whisked away to the Delta Quadrant by the advanced entity. The missile drifted on a rough course back towards the Alpha Quadrant, but it had suffered some damage to its computer and sensor systems that altered the way it perceived potential targets. It attacked and destroyed an unarmed transport before locking on to the nearby planet of Rakosa V, an inhabited world.

Fortunately, the USS Voyager was nearby, having also been abducted by the Caretaker the year before, and B'Elanna Torres was on board. She used her familiarity with the missile's systems to board the weapon and instruct it to deactivate. Torres then returned to Voyager, and the crew made plans to dismantle the weapon and salvage its parts.

Dreadnought's computer had other plans, though. Back in the Alpha Quadrant, Torres had programmed the computer with 39 different possible security breaches, including the possibility that Torres herself was coerced into cooperating with either the Cardassians or the Federation and attempting to stop the missile from attacking its target. The computer accused Torres of collaborating with the Cardassians.

Dreadnought is attacked by the Rakosan defensive fleet

As the missile approached Rakosa V, it was confronted by a small fleet of fifteen defensive fighters; even with the Rakosans receiving support from Voyager, they were vastly outgunned and quickly forced to withdraw. Torres used the diversion to activate the latent Cardassian computer programming, which attempted to retake control of the missile. Torres' Maquis program initiated countermeasures, attempting to wipe out the attacking "virus". Torres then took the opportunity to work her way into the missile's warp core, where she used her phaser to burn her way through the reactor core's shielding.

As Torres was attempting to destroy the magnesium casing on the warp core, Captain Janeway ordered her crew to abandon Voyager and prepared to activate the ship's auto-destruct sequence, ready to sacrifice her ship and herself to save the planet. Torres succeeded in destabilizing the core, and Janeway canceled the sequence just a minute before the explosion. Torres herself was beamed out at the last second, as the missile exploded in orbit of Rakosa. (VOY: "Dreadnought")

The missile interior was designed by Richard James. An extreme number of fluorescent lights were built into the set, so that director LeVar Burton could film there with a hand-held Steadicam without being encumbered by equipment in the way, allowing the production crew to film more quickly on the set. (Star Trek: Communicator, issue #108, p. 49)

In Star Trek: Armada II, the Dreadnought missile appeared as a Cardassian superweapon. Upon impact with its target, it created a spatial rift that destroyed any ship or station within its radius. If destroyed by enemy fire, however, it would explode normally with no damage to nearby structures.